Synthetics generally have better flow properties than conventional, but this doesn't do much good if your oil filter restricts the flow rate. K&N filters have a much higher flow rate, and filter to smaller micron measurement than most filters. Also, they have an anti drain back valve that keeps oil in the filter so when you start your truck it will lubricate and circulate oil faster.
All of that = good

I have a K&N on my 07 4.0. I also switched to Mobile 1. The filter is a little pricey as is the oil. But as the old saying goes "You get what you pay for". If you plan on keeping the truck I recommend the combo but if you lease or trade in quickly then I think it's a waste of your money.

I have a K&N on my 07 4.0. I also switched to Mobile 1. The filter is a little pricey as is the oil. But as the old saying goes "You get what you pay for". If you plan on keeping the truck I recommend the combo but if you lease or trade in quickly then I think it's a waste of your money.

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Well said, the trucks will last a long time anyway, so if you don't keep it forever then synthetic and k&n are a waste, but if you want it to last you a couple decades then the switch is a good idea.